compareExchange -- compares and possibly exchanges the value of an atomic integer

Synopsis

Usage:

compareExchange(x, y, z)
Inputs:
- x, an atomic integer,
- y, an integer,
- z, an integer,
Outputs:
- a Boolean value,

Description

The values of x and y are compared. If they agree, then true is returned and the value of z is stored in x. Otherwise, false is returned. This operation occurs atomically and is thread safe.

i1 : x = new AtomicInt

o1 = 0

o1 : AtomicInt

i2 : compareExchange(x, 2, 3)

o2 = false

i3 : x

o3 = 0

o3 : AtomicInt

i4 : compareExchange(x, 0, 3)

o4 = true

i5 : x

o5 = 3

o5 : AtomicInt

Ways to use compareExchange :

compareExchange(AtomicInt,ZZ,ZZ)

For the programmer

The object compareExchange is a method function.